Practical Oppenauer (OPP) Oxidation of Alcohols with a Modified Aluminium Catalyst
Takashi Ooi, Hidehito Otsuka, Tomoya Miura, Hayato Ichikawa and Keiji Maruoka*
*Department of Chemistry, Graduate School of Science, Kyoto University,
Sakyo, Kyoto 606-8502, Email: maruoka
kuchem.kyoto-u.ac.jp
T. Ooi, H. Otshuka, T. Miura, H. Ichikawa, K. Maruoka, Org. Lett., 2002, 4, 2669-2672.
DOI: 10.1021/ol020094c
Abstract
An effective protocol for Oppenauer (OOP) oxidation of alcohols under mild conditions with t-BuCHO as hydride acceptor was developed. The highly active aluminium catalyst allowed even the oxidation of terpenoids and stereoids with acetone as the hydride acceptor.
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Details
The document discusses a study on the practical Oppenauer (OPP) oxidation of alcohols using a modified aluminum catalyst. The researchers found that the aluminum catalyst 2 is highly effective for OPP oxidation under mild conditions. For instance, the oxidation of carveol in toluene with t-BuCHO as a hydride acceptor and 1 mol% of catalyst 2 at 21°C yielded carvone in 94% after 1 hour. This method is advantageous due to its operational simplicity, use of inexpensive and non-toxic reagents, and high functional group compatibility. The study also explored the oxidation of various alcohols, including secondary aliphatic, allylic, and benzylic alcohols, yielding good to excellent results. The use of acetone as a hydride acceptor was also examined, showing promising results with only 1.2 equivalents of acetone needed. This new method addresses the limitations of previous aluminum-based OPP oxidation systems, which required large amounts of acetone and continuous heating. The study highlights the potential of this catalytic system to meet economic and environmental requirements for fundamental functional group transformations. Further improvements and applications to natural product synthesis are under investigation.
Key Words
Oppenauer Oxidation, Meerwein-Ponndorf-Verley Reduction, Pivaldehyde, Acetone
ID: J54-Y2002-500
